1. Field of the Invention
The present invention relates to a pulse width modulation (PWM) signal generating circuit and a motor driving circuit, capable of being applied to a fan motor and adjusting a proportional-to-absolute temperature (PTAT) voltage used to generate a PWM signal.
2. Description of the Related Art
Generally, in order to drive a fan motor, a motor driving circuit includes a pulse width modulation (PWM) signal generating unit generating a PWM signal and a driving unit generating a driving signal using the PWM signal.
Here, the PWM driving unit adjusts a duty ratio of the PWM signal according to a degree of heat radiation of a motor driving circuit to decrease an influence thereon due to the heat radiation.
Meanwhile, a motor driving circuit according to the related art includes a temperature sensor in order to compensate for an influence thereon due to a temperature change in the motor driving circuit.
The temperature sensor may detect the temperature change in the motor driving circuit. However, it may be difficult to integrate the temperature sensor with the motor driving circuit for miniaturization in the motor driving circuit.
In addition, an output value according to a temperature range that may be detected by the temperature sensor is fixed, such that it may not be appropriately adjusted according to a state of a product to which the temperature sensor is applied.
The following Related Art Document (Patent Document 1), which relates to a temperature compensation type oscillator, may provide a proportional-to-absolute temperature (PTAT) voltage simply using a transistor, but does not disclose a technical feature of adjusting the PTAT voltage using a control signal.